Glossary

static equilibrium

a state of equilibrium in which the net external force and torque acting on a system is zero

dynamic equilibrium

a state of equilibrium in which the net external force and torque on a system moving with constant velocity are zero

8.2 Torque

torque

turning or twisting effectiveness of a force

perpendicular lever arm

the shortest distance from the pivot point to the line along which [latex]\mathbf{\text{F}}[/latex] lies

SI units of torque

newton times meters, usually written as N·m

center of gravity

the point where the total weight of the body is assumed to be concentrated

8.3 Stability

neutral equilibrium

a state of equilibrium that is independent of a system’s displacements from its original position

stable equilibrium

a system, when displaced, experiences a net force or torque in a direction opposite to the direction of the displacement

unstable equilibrium

a system, when displaced, experiences a net force or torque in the same direction as the displacement from equilibrium

8.4 Applications of Statics, Including Problem-Solving Strategies

static equilibrium

equilibrium in which the acceleration of the system is zero and accelerated rotation does not occur

8.5 Simple Machines

mechanical advantage

the ratio of output to input forces for any simple machine